-
Financing available — foam insulation from $99/month. See options
Veteran owned · Serving Southern Wisconsin
$2,500 flat — any size home.
Standard 2-inch closed-cell spray foam around your entire rim joist. Adding it to a wall insulation job? It’s just $2,000.
The rim joist (also called the box sill or band joist) is at the top of your basement wall, where the floor joists rest on the concrete foundation. Between the joists sits an empty cavity, with only a thin board between your basement and the outside air. In most Wisconsin homes that space was never sealed or insulated. Cold air, moisture, and mice come straight through it, and square foot for square foot it is one of the biggest sources of heat loss in the whole house.
An uninsulated rim joist turns your floor joists into wind tunnels in the winter. Cold air pours in at the top of the foundation and runs straight down the joist bays, right under the floors you walk on, making your floors freezing cold.
Cozy Walls seals and insulates rim joists with closed-cell spray foam, which stops the air leak and the heat loss in a single application.
Outside air enters at the rim, cools the floor framing, and you feel it through the floor above.
Warm air rises and escapes through the attic, and cold air gets pulled in at the bottom of the house to replace it. The rim joist is the main entry point.
Your furnace isn’t losing to the walls as much as you’d think — it’s losing to air movement.
Humid summer air hitting cold framing condenses. Over years, that means musty smells, mold, and rot in the band board and sill plate.
Almost every home we open up has fiberglass stuffed into the rim joist cavities. It looks like insulation. It isn’t doing the job.
We inspect the full rim joist perimeter, identify problem areas, remove existing fiberglass when necessary, and apply closed-cell spray foam to seal the rim board and sill plate.
We inspect the full perimeter, note any water damage or rot, measure linear footage, and identify obstructions — ductwork, wiring, plumbing runs.
Existing fiberglass gets removed and hauled away. Surfaces are cleaned and any obvious moisture issues are flagged before we spray.
Closed-cell foam is applied to the rim board and across the sill plate, sealing the joint where the framing meets the foundation. We follow Wisconsin code requirements for thermal and ignition barriers where they apply.
We clean the work area and walk the job with you before we leave. Most rim joist jobs are completed in a single day. The foam is tack-free within minutes and fully cured within hours.
The foam expands into every gap, seam, and irregular corner, then cures solid. The leak is gone.
At two inches or more, closed-cell foam blocks moisture from reaching the cold framing, so condensation never forms.
Roughly R-6.5 to R-7 per inch — the highest of any commonly installed insulation, which matters in a shallow cavity where you don’t have much depth to work with.
and won’t sag, settle, or absorb water over time.
No. Building code only calls for a mechanical fresh-air system once a home tests below 5 air changes per hour on a blower door test (ACH50). Most older Wisconsin homes test at 12 or more, and Wisconsin requires a new home to come in under 7. Sealing the rim joist closes the worst leak in your basement, but your home still exchanges air through the attic, windows, doors, and every other opening.
What we stop is the cold draft at your floor line, not your home’s fresh air. Want proof? Our blower door test measures your home before and after, so you see the number for yourself.
We’ll flag it during the walkthrough. Foam over rotted framing just hides a problem. If we find structural damage, we’ll tell you before we quote the work.
Yes. The same air leak that lets cold in during winter lets humid air in during summer, which loads up your air conditioner and raises basement humidity.
